Better way of saying "this is because"

I am writing the following

Previous work on Topic Detection and Tracking (TDT) has achieved great success on full length document, but the techniques has yet to be fully implemented on microblogs. This is because the sources of TDT are news articles which already contains news information and structured...

I am trying to avoid joining them using a comma, as it will turn out to be a very lengthy sentence. At the same time, I wish to reduce "this is because" to a shorter version (preferably 1 word). I tried to remove it but it sounded odd and did not flow together well.

Can I get some suggestions, please? Thanks.

Solution 1:

There’s nothing wrong with ‘This is because . . .’, but an alternative would be ‘The reason is that . . .’ I don't know of any single word that would be suitable.

You might want to change document to documents and has to have.

Solution 2:

How about:

"Previous work on Topic Detection and Tracking (TDT) has achieved great success on full length document. However, the techniques has yet to be fully implemented on microblogs, because the sources of TDT are news articles which already contains news information and structured..."

?

Solution 3:

The actual answer to your question is since. But I agree with those posters who think that reducing the word count by two is not worth the long, clumsy sentence that will result.